1. Field of the Invention
The invention relates generally to the field of electro-optical sensors that operate in multiple spectral bands.
More specifically, the invention relates to an electro-optical sensor that operates on a large imaging field of view and measures the spectral content of the entire image field of view in a series of sequentially sampled, selectable spectral sub-bands whose operation is adaptable in real-time based on analysis of measured image content, on environmental conditions and on the instrument user-defined priorities for obtaining information.
2. Brief Description of the Prior Art
Imaging spectrometers generally operate with an array of detectors each of which is seeing different spectral content as the sampled light is spectrally dispersed across the array by an optical element such as a prism or diffraction grating. The array is then scanned over an image field of view thus creating images of the field of view in spectral sub-bands. Such sensor systems may operate in spectral sub-bands of varying spectral width and are described as “multispectral imagers” if the sub-bands are fairly wide and as “hyperspectral imagers” if the sub-bands are very narrow. This class of imaging spectrometer does not provide a map of the intensity content of a spectral sub-band obtained over a large image field that is obtained at the same instant of time, i.e., in real time. An additional sensing technique, Fourier interferometry, makes use of spatial patterns to modulate the image fields in time thus encoding various spectral band content into different temporal frequencies that can be detected and isolated creating spectral sub-band maps. This technique requires the creation of interference patterns that make such sensor systems inefficient and still does not provide a spectral sub-band image across the field of view at the same instant of time. In the current state of the art of imaging spectrometers, adaptive control for how the instrument allocates its time between various spectral regions is determined by the hardware elements of the sensor design and does not permit adaptive control of the spectral sampling.
What is needed is a high resolution imaging spectrometer that can obtain a spectral sub-band image across a large field of view at a single instant of time. Further, the high resolution imaging spectrometer should be capable of rapidly and sequentially obtaining many sub-bands of images across a large field of view in a temporal sequence of images. Such an instrument will provide full spatial, temporal, and spectral maps of a large imaging field of view, preserving the maximum information content of the observed field of view. This class of instrument will produce a very large amount of data, much of which is often not relevant to the data being taken by the instrument. Adaptive control of how the spectral data is taken to maximize the effectiveness of data-taking based on observing conditions and user priorities is needed.